This invention relates generally to bag structures, and more particularly, to bag structures having improved loading and tamper evident features.
Bag structures may be fabricated from a single ply of material or from multiple plys or layers. The bag structures may be fabricated from paper or plastic materials. Typically, multiwall bags are fabricated as tubes formed from a plurality of paper plies. In addition to having paper plies, one or more plies, typically the innermost one or more plies, may be fabricated from a thin plastic material, or may be coated with a resinous material, to provide a degree of moisture resistance to the finished bag.
Closure of the multiwall bag structures are typically accomplished by applying adhesive (e.g., hot melt or sonically activatable adhesive) to the outer surface of the bag and folding over the top end. Closing the bag by simply folding and adhesively affixing the flap provides a pointed, pinch bottom closure. The opposite end of the bag may be likewise provided with a pinch bottom closure, or it may be closed and sealed in a different configuration, such as a diamond-or rectangular configuration, so that the pinch “bottom” may actually be the top of the bag, as may be found commonly in bags containing dry granular material, like dog food, cat litter or fertilizer. When such a bag is closed and sealed, the folded over closure is typically quite strong, and requires cutting of the bag plies below the folded over and sealed closure, in order to gain access to the contents of the bag. Moreover, once such bags are opened, the bags can not be reclosed or resealed. As such, the contents of the bag may spoil quickly or are susceptible to spillage through the opening.
In order to facilitate opening and closing of bag structures, such as flexible bags, some bag structures are known that incorporate a zipper that may be opened and closed. At least some of these known bag structures also include a slider to aide in opening and closing of the zipper. However, these known bag structures are typically included on flexible bags and bags that are top loaded. When a bag is top loaded, the product loaded into the bag does not contact the zipper during loading. As a result, the zipper is protected from any impact of loading the product into the bag. However, other known bag structures are bottom loaded, such as bags loaded with dry granular material, like dog food, cat litter or fertilizer. Because these bags are bottom loaded, the zipper at the mouth of the bag is susceptible to damage or rupture during loading of the product into the bag.